Lenders pay close attention to your income and factors that might impact it, such as job stability, investment income volatility, and existing debt. They assess your debt-to-income (DTI) ratio to determine your mortgage affordability. The DTI ratio calculates the portion of your gross income used to pay off debts, including credit cards, car loans, student loans, and any current or prospective mortgages. For example, if your monthly gross income is $6,000 and your total monthly debt payments are $1,500, your DTI is 25%. A DTI of zero means you have no debt.
Most mortgage lenders adhere to DTI limits set by Fannie Mae and Freddie Mac, allowing a DTI up to 50%. This means with a $6,000 monthly income and $1,500 in debt payments, you could qualify for a mortgage costing up to $1,500 monthly. Without any debt, you could afford a $3,000 monthly mortgage. Reducing debt before applying for a mortgage can significantly increase the loan amount you qualify for. However, the 50% DTI cap was established in 2017, increasing from previous limits of 45% in recent years, 40% a decade ago, 36% twenty-five years ago, and 30% fifty years ago.
Why have DTI limits increased over time? The reason is straightforward: without higher DTI limits, fewer individuals could qualify for mortgages due to the faster rise in home prices compared to incomes. This scenario would lead to fewer home sales, affecting the income of bankers, realtors, and builders. Consequently, the real estate industry has pushed for higher DTI limits to promote home ownership, benefiting their interests.
However, there is a wide gap between what the mortgage industry says you can afford and what your budget can actually carry. Treat the lender’s DTI as a ceiling, not a target — it is the largest loan they are willing to write, and writing large loans is how they profit. What you should commit to is stricter. The rest of this section gives you three progressively tighter personal yardsticks — the housing ratio, the broad housing ratio, and the 30/30/3 rule — and one cautionary subsection (section “The Gross-DTI Trap for High Earners in High-Tax States”) that you cannot skip if you live in a high-tax state. Use the lender’s number only to learn the ceiling; use the rules below to decide how far beneath it to stay.